像素放大题

师兄的一道笔试题

我的代码

#include<iostream>
#include<vector>

using namespace std;

int main()
{
 int M{ 0 }, N{ 0 };
 cin >> M >> N;
 vector < vector<int>>v{};
 v.resize(M);
 vector < vector<int>>v1{};
 v1.resize(M*N);
 //构造原始矩阵
 for (int i = 0; i < M; ++i) {
  for (int j = 0; j < M; ++j) {
   int x;
   cin >> x;
   v.at(i).push_back(x);
  }
 }


 for (int i = 0; i < M*N; ++i) {
  int j = i / N;//对应原矩阵的行
  for (int k = 0; k < M; ++k) {//对应原矩阵的列
   for (int m = 0; m < N; ++m) {
    v1.at(i).push_back(v[j][k]);
   }
  }
 }

 for (int i = 0; i < v1.size(); i++)
 {
  for (int j = 0; j < v1[i].size(); j++)
  {
   cout << v1[i][j] << " ";
  }
  cout << endl;
 }
 cout << endl;
 return 0;
}